Thermally Driven Mechanical Actuators by Using Absorption/Desorption of Metal Hydrides: A Comprehensive Simulation

Metal hydrides have been investigated for use in a number of applications, such as heat regenerators, thermal compressors, and hydrogen storage. McKibben actuators are pneumatic actuators that have unique characteristics, such as biomimeticity (having force/deflection characteristics similar to natural muscles), compactness, high force-to-mass ratios, and moreover are lubricationless, noiseless, soft actuating, and environmentally benign. Actuators with these characteristics are ideal for many industrial, space, defense, robotic, and biomedical applications. The combination of metal hydride technology with McKibben actuators builds on the advantages of both technologies, while mitigating the deficiencies of each. In this paper, we report results from a comprehensive simulation strategy for a LaNi_4.3Al_0.7 based McKibben actuator. The simulations are able to predict and characterize the performance bounds of the actuator in terms of actuator time/thermal input, power/efficiency and force/displacement diagrams. The advantages and disadvantages of the design are discussed from these perspectives.